Universiteit Leiden

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Research project

Empirical Legal Studies

For the legal science theme Empirical Legal Studies, Leiden has chosen the topic ‘markets, behaviour, and the regulatory role of the law’ as its starting point to advance empirical legal research.

2019 - 2024
Helen Pluut
Ministry of Education, Culture and Science

Empirical Legal Studies is one of the two legal science themes of the Dutch national sector plan for law, the other being Institutions for Conflict Resolution.

The regulatory role of the law can be seen in economic reality where, ideally, the market ensures that supply and demand converge. Legal reality operates within this economic reality. It can ensure that markets function efficiently and fairly.

Market forces, after all, might lead to unfair outcomes for market actors, society, or the environment. The law aims to nurture trust in the markets, solve shortcomings in information, prevent negative externalities of transactions, and fight excessive market concentration.

In order to make regulations in such a way that they can prevent market failure, it is important to properly understand how markets operate in practice and how market actors think, decide and act. There is often a lack of knowledge in these areas. We do not always know which legal rules work, under what circumstances, and why.

Empirical research on law in action provides essential knowledge about behavioural assumptions underlying various legal rules. Empirical legal research, including applied economic, psychological and sociological research, not only has added value for the empirical ‘what, when, and how’ questions, but also for the normative ‘and what do we think of this’ questions.

By answering empirical questions, the research in this legal science theme provides building blocks for answering normative questions regarding market regulation. Therefore, the focus is on the interaction between empirical and normative questions.

Research projects

Two PhD projects started in March 2020. Both are interdisciplinary PhD projects that are supervised by researchers from at least two departments and by both a legal scholar and a social scientist. The other projects within this legal science theme involve lines of research by assistant professors.

For many years, human rights have been considered a playing field in which states were the most important actors. In the present day society, this has changed as a consequence of globalization and the rise of multinational enterprises (MNEs). Protection of fundamental labor rights in global supply chains is a concern. This project focuses on multinational companies as market actors and the regulation of their behaviours in global supply chains. Monitoring the behaviours and actions of multinationals has become more complex because international organisations such as the United Nations and the ILO are losing territory. In this context, it is important to look at soft law. Codes of Codes of conduct are a set of rules voluntarily drawn up by companies but with which they must comply. What role do these Codes of Conduct play in compliance with and enforcement of fundamental labor rights in global supply chains?


The data-driven economy allows for the collection and processing of large amounts of data. Such data can be used to optimize profits by (dynamically) differentiating prices for different consumers. It is now technologically feasible for webshops to set prices that perfectly match the consumer’s willingness to pay. What does this imply for trust in markets? What do companies and consumers think of this, and how should regulatory actors respond? The aim of this project is to gain insights into the psychology of companies and consumers. Empirical research on perceptions of justice can form an important basis for the normative dimension of market regulation


The starting point for this research project is the notion that the human brain is susceptible to all kinds of fallacies and biases that affect our perceptions and influence our reasoning outside of our conscious awareness. Indeed, most people think they are merely observing facts and that they process these in a rational, objective way to form judgements and make decisions.

In the field of law, perceptions and decisions that are erroneously affected by unconscious biases can have far-reaching consequences. Consider for example the question of whether a type of damage (e.g. economic or personal injury) was foreseeable, or whether a director’s actions played an important role in causing a company to go bankrupt, or whether certain information was of such a material nature that a reasonable investor would make use of it when taking investment decisions. Judgements about foreseeability, causality, and reasonableness are particularly susceptible to human biases. Research by Niek Strohmaier has shown that especially moral and normative judgements can influence these kinds of legally relevant issues. This interdisciplinary and empirical research project draws on insights from moral philosophy, cognitive psychology, and insolvency law in particular.

Niek’s line of research focuses on three topics. First, Niek empirically investigates which biases might affect legal judgments in the context of directors’ liability and in the context of regulating financial markets. Second, by conducting experimental research, Niek aims to increase our understanding of the mechanisms underlying certain biases. Third, his research explores how we might be able to minimize the unwanted impact of biases in legal judgments and decision making.



European product safety law is one of the focal points of internal market legislation. The main goal of European product safety law is the prevention of harm from occurring. Product safety law’s market surveillance and enforcement is left to the member states. The obligations for economic operators therein are seen as being of a more public law nature (opposed to private law). The private law counterpart of product safety law is the Product Liability Directive (85/374/EEG). Compensation under this internal market instrument is presumed not only to have a restorative function, but also to have some deterrent effects. The remedy under the Product Liability Directive is limited to liability for consequential loss to property and physical harm. The requirements for other private law remedies with regard to other types of damages and other tortfeasors are not harmonized and left to the member states. Until now it is unclear how effective the current legal framework is in the prevention of damage by combatting illegal product and to prevent damage from occurring. Because of e-commerce, traditional chains of trade are changing and new economic operators are entering the scene. These changes highlight deficiencies in het current legal framework and raise the question which (legal) interventions are most appropriate, effective and efficient to combat unsafe products.

This line of research builds upon Gitta’s earlier doctrinal research regarding the interaction between European Product Safety Law and standards under private law. It aims to contribute in answering the overarching question of the effects of private law in the prevention of harms from occurring, with a focus on unsafe products. Both B2B- and B2C-relationships are included. What are the driving forces within organizations and companies in the chain that influence the decision of placing an unsafe product on the market or withdrawing, or of recalling a product that has already been placed on the market and turns out to present a risk? And which role does the consumer himself play? Which factors influence his online purchase decisions?

This interdisciplinary, empirical research uses the insights from law and economics and behavioural sciences and is performed in collaboration with social scientists. It aims at testing some of the assumptions that underly legislation and legal decision making, which hopefully contributes to a better assessment of (legal) interventions to reach desired effects and more evidence based private law. 


ELS Lab @Leiden activities

The Empirical Legal Studies Lab @Leiden is organizing a new series of sessions, for researchers interested in empirical legal research. Are you looking to learn more about empirical methods and/or engage in lively discussions on ELS? Join the upcoming ELS lab meetings!

Ranging from the informal Lunch & Learn to more in-depth paper discussions, the ELS lab meetings cover a wide range of empirical research methods and ELS-related topics. We offer a possibility to learn about each other’s research and experience, test out ideas and receive feedback on work in progress. You’re welcome to join, regardless of your degree of experience with ELS.

Find more information about the lab meetings below. This semester, we are continuing our series from last academic year.

Lunch & Learns are informal, interactive sessions where we discuss a controversial statement relating to an ELS-themed topic. It is an opportunity to share your opinion and experiences with regard to doing empirical legal research and to learn from peers.

The upcoming Lunch & Learn will take place on 21 October (12:00-13.00) on the topic ‘from legal scholar to empirical legal scholar’. Please join us for this informal session; everyone is welcome to participate in the discussion, no matter your level of expertise.

The upcoming Work in Progress Session will take place on 3 December (10:00-11.00). Niek Strohmaier and Sofia de Jong will discuss their research on the biasing effect of character evidence in legal decision making and procedural justice. n.

The upcoming Journal Club will take place on 12 November (10:00-11.00) on the topic ‘designing vignette studies – tips and tricks’’. The dissertation by Shosha Witznitzer on defensive doctors will be taken as a starting point for the discussion.


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